On the structure of palau'amine: Evidence for the revised relative configuration from chemical synthesis

Journal of the American Chemical Society

Volumn 129, Issue 42, 2007, Pages 12896-12900

  Lanman, Brian A ^a,b   Overman, Larry E ^a   Paulini, Ralph ^a   White, Nicole S ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

^b AMGEN INC   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALKALOIDS; HEXACYCLIC DIGUANIDINE STRUCTURES; NMR DATA;

FUNCTIONAL GROUPS; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; SYNTHESIS (CHEMICAL);

AMINES;

BICYCLO[3.3.0]OCTANE DERIVATIVE; GUANIDINE DERIVATIVE; PALAUAMINE; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL ANALYSIS; CHEMICAL STRUCTURE; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; STRUCTURE ANALYSIS; SYNTHESIS;

CARBON; CHEMISTRY, ORGANIC; DIMERIZATION; GUANIDINE; GUANIDINES; MAGNETIC RESONANCE SPECTROSCOPY; MODELS, CHEMICAL; MOLECULAR CONFORMATION; MOLECULAR STRUCTURE; OCTANES; PYRROLES; SPIRO COMPOUNDS; STEREOISOMERISM; TEMPERATURE;

EID: 35548960983     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja074939x     Document Type: Article

References (35)

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14. (c) Grube, A.; Köck, M. Angew. Chem., Int. Ed. 2007, 46, 2320-2324. The relative configuration of the C20 stereogenic center was assigned as shown for 1 in the initial isolation report (ref 2a), then corrected in the following publication (ref 2b). All congeners of palau'amine were assigned the initial relative configuration at C20 (refs 2c,d, 4a-c).
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21. Prepared from potassium thiocyanate and benzyl chloroformate according to: Wang, S. S.; Magliocco, L. G. American Cyanamid Company. US Patent 5194673, 1993 (see the Supporting Information).
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27. The configuration of the hemiaminal stereocenters was elucidated by 2D NMR experiments (see the Supporting Information).
28. 2 and in protic solvents.
29. The simultaneous removal of the TBS ether is undoubtedly facilitated by the hemiaminal hydroxyl group, because desilylation does not occur in cyclizations of related substrates in which C21 is at the carbonyl oxidation state.
30. 4, and carefully concentrating the dried solution in vacuo.
31. Among the publications on palau'amine and related structures, an H11/H12 NOE correlation was only mentioned for konbu'acidin A and tetrabromostyloguanidine (refs 2d and 4c).
32. Interproton distances were obtained from NOESY spectra with different mixing times (100, 150, and 200 ms). Intensity data from volume integration of NOESY crosspeaks were calibrated using the geminal proton pair at C13 (178 pm). Each NOESY spectrum was analyzed separately (linear approximation, verified by a linear relationship between volume integrals for different mixing times).
33. In all cases conformational searches were carried out to determine global minima. Only minima lacking intramolecular H-bonds were considered for calculations using Spartan 04. These results are given in the Supporting Information.
34. General experimental details are provided in the Supporting Information.
35. 1H-NMR)).